Subproject 2 will determine the role(s) of integrins as regulators of opioid receptor organization and function in mature primate and human trigeminal ganglion neurons. Cells interact with the extracellular matrix via heterodimeric transmembrane receptors, termed integrins. Integrins are involved in the regulation of vital cell functions, including adhesion, migration, and gene regulation. Though several studies have provided strong evidence that specific integrins are vital to the normal development of the central and peripheral nervous system, there is little information available concerning the functional significance of integrins expressed by mature sensory neurons. This is an important gap in knowledge since our preliminary data indicate that opioid receptor function in trigeminal ganglion neurons is disrupted by blockage of the arginine-glycine-aspartate-binding (RGD) class of integrins. Therefore, we will determine which of the known RGD-binding integrins mediate these effects in mature primate trigeminal ganglion neurons in Specific Aim #1. In Specific Aim #2, we will evaluate potential mechanisms that may be involved in integrin-dependent opioid inhibition of PGE2-mediated adenylate cyclase signaling. We have observed that bradykinin-priming renders competent opioid receptors expressed by cultured trigeminal ganglion neurons, as assessed by opioid inhibition of PGE2-mediated adenylate cyclase signaling. Interestingly, we show that integrin antagonists (i.e., RGD peptides) block opioid signaling in bradykinin-primed trigeminal ganglion neurons. These findings are consistent with the hypothesis that the inflammatory mediator bradykinin elicits an effect on neuronal integrins that, in turn, modulate opioid receptor function. In Specific Aim #3, we will investigate integrin expression and activation in cultured trigeminal ganglion neurons stimulated by bradykinin. Finally, in Specific Aim #4 we will investigate integrin-dependency of opioid receptor function in human nociceptors found in normal and inflamed tissues. This sub-project should greatly increase our knowledge regarding: 1) integrin expression by mature sensory neurons, specifically trigeminal ganglion neurons, and 2) the role(s) of specific integrins in the regulation of opioid receptor function in trigeminal ganglion neurons. This information will elucidate a novel function of integrins (i.e., regulation of opioid receptor function in trigeminal ganglion neurons).